1. Field of the Invention
The invention generally relates to wind-resistant overhead rolling doors, and, more specifically, such a overhead rolling door which has an improved retainer for securing the edges of the slats making up the door and providing improved wind lock protection.
2. Description of the Prior Art
Closure devices for protecting openings in building structures, such as doors and windows, are frequently relied upon not only to provide security for the building structure by preventing unauthorized access to the structure, but are frequently also relied upon to protect the structure from severe natural climatic conditions. To the extent that doors and windows are made of glass, these are particularly susceptible to certain atmospheric conditions. Glass, which is frequently used to close openings in building structures, is not only susceptible to damaged flying debris during such adverse climatic conditions, but can also be destroyed as a result of dynamic and/or static air pressure differentials on the two sides of the windows, doors, or the like. As a result of the dangers posed by these natural climatic conditions, a number of states and local governments have enacted rules and regulations in order to prevent or minimize damage. The State of Florida, for example, has enacted such regulations and building codes due to the frequent occurrences of hurricanes in a number of counties in Florida, such as Dade and Broward Counties.
One approach to reducing the problem has been the use of shutters which are hingedly mounted on each side of the opening of the structure. However, such shutters, to be effective, have to be made of heavy materials such as steel, and are not conducive for automatic operation and are relatively expensive. Rolling, slatted doors and shades have also been used. These are typically rolled up in a coil at the top of the opening and unrolled to cover the entire opening exteriorly of the glass windows and doors. While such rolling closures have been effective to prevent impact by flying debris, they typically flex or bend when subjected to positive or negative pressures on the outside of the structure. However, such bending or flexing of the slats outside of the plane of the building structure effectively shortens the lengths of these slats by moving the ends inwardly, particularly on the sides and on the bottom of the door. While some known designs have attempted to limit the lateral inward movements of the ends of the slats, to thereby prevent excessive bowing or flexing of the slats outside the plane of the rolling closure, the effectiveness of the design depends, to a great extent, on the integrity and strength of the connection between the lateral ends of the slats and the end or edge retainers mounted on the slats. Such retainers are designed to be guided within guide channels provided in the vertical side portions of the frame of the door. One example of such a design is illustrated in U.S. Pat. No. 5,657,805 for a wind-resistant overhead closure. This patent is primarily concerned with minimizing the flexing or bending of the lowermost or bottom slat or slats of the door. However, the retainer, of the type shown in FIG. 7 of the patent, includes a single flat mounting portion which is attached to the lateral edge of a slat. When such flat mounting portion is attached to the flat portion of the slat by means of a suitable fastener, such as a rivet, it will be clear that the strength of the connection will be a function of the single shear strength of the rivet or rivets used to make the connection. Also, because the retainer members are generally mounted for free movements within the guide channels, there are provided clearances between the retainer and the vertical side frame members, severe wind loads, causing the slats to flex or bend a substantial amount may cause the retainers to be dislodged from the guide channels, severely compromising the ability of the door to protect the enclosure.
In U.S. Pat. No. 1,918,415, a combined bracket and guide for rolling steel doors is disclosed, an end lock is provided which closely abuts the rolled edges of the slats to prevent the plates from moving longitudinally in relation to each other, and also includes an L-shaped bracket provided at spaced intervals on selected slats arranged to engage behind one of the legs forming the guide channel in order to maintain the position of the door in relation to the guide channels. However, the bracket which forms the wind lock is a simple L-shaped bracket secured by means of rivets to one side or planar portion of the slat. The strength of the connection of the slat is, as with the previously described design, a function of the single sheer force of the rivet or rivets used. Also, any forces applied to the wind lock in the design of this patent act to separate the wind lock from the slat, placing the rivet or rivets in tension, creating another possible mode for failure. A similar construction is disclosed in U.S. Pat. No. 3,076,499 which discloses a rolling metal door. A sealing and guiding structure for a door is disclosed in U.S. Pat. No. 3,489,200, which also discloses a similar construction. Wind locks in the form of bent brackets mounted on one side of selected slats by means of bolts are disclosed in U.S. Pat. No. 3,734,161, for a door construction.
In U.S. Pat. No. 5,253,694, a rolling shutter slat and retainer is disclosed in which the retainer mounting portion is received between two spaced panels or plates forming a single slat. While such construction strengthens the connection between the retainer and the slat to withstand double the sheer forces, the slat disclosed is non-conventional, not in common use and substantially more expensive than single panel, conventional slats. Also, application of significant forces on the retainer would appear to cause the retainer to pivot or rotate in relation to the slats about the rivets, tending to separate the two panels forming the slat, instead of applying gripping or holding forces thereto.